The present invention relates generally to a copying system comprising a tracer for tracing automatically a contour of a pattern to be traced and a working machine for effecting a given working for an object with a working head being moved in conjunction with the tracer with a given relationship. More particularly it relates to a method for controlling an operation of the copying apparatus and an apparatus for carrying out the method.
As an example of such a copying apparatus a copy-gas cutting apparatus has been known, the device comprises a tracer for tracing automatically a contour of a pattern described on a template and a gas torch assembly having at least one blowpipe for jetting a cutting oxygen flow against an object such as a steel plate. In operation the steel plate is cut by the oxygen flow from the torch, while the tracer follows the pattern on the template in a mechanically contacting or photoelectrically non-contacting manner. In this manner an article or workpiece having the same shape as the pattern of template can be automatically cut out of the steel plate.
In the case of working the object, i.e. the steel plate with such a copy gas-cutting apparatus, the tracer is at first positioned manually at a point which is slightly remote from the pattern on the template and the gas torch assembly is operated to form a hole in the steel plate. This operation is sometimes referred as piercing. Then the tracer is manually moved from the piercing point to a copy start point on the pattern, while the oxygen gas flow is ejected from the torch, i.e. the cutting operation is continued. After that the tracer traces automatically the template and the steel plate is cut accordingly. When the tracer reaches a tracing end point, the ejection of cutting oxygen flow is stopped and then the tracer is removed from the template. In the known copying apparatus an operator must stay always near the apparatus to control manually the movement of the tracer and the operation of the gas torch. Therefore the known operation is very cumbersome and working efficiency is very low. Particularly in the case of effecting a series of operations with using a plurality of patterns after the operation for a pattern has been finished, the operator has to move the tracer to a next pattern. Such treatment is quite hard to manage.
In order to obviate the above mentioned drawback there has been devised a copying apparatus in which a tracer follows automatically from an end point of a pattern on a template to a start point of a next pattern along a guide line described on the template. In this case it is necessary to prepare special templates on which guide lines have been described and thus ordinary templates which have been used heretofore could not be utilized. Since the template requires a very high accuracy the upmost care should be taken in manufacturing the same. Therefore its process is quite complicated and results in high cost. Further in actual operation it is sometimes undesirable to predetermine the piercing points, start points and end points in accordance with the shape and material of objects to be worked, shape of pattern, arrangement of patterns in case of using a plurality patterns. In such a case the template having the guide line previously described thereon could not be used and the operator must move the tracer manually or a new template having a new guide line described thereon has to be prepared. In either cases the working efficiency becomes lower to a great extent.
Further there has been developed a so-called numerical control system in which position of the working machine with respect to the object are previously set as numerical values which are then stored in a memory as a given program. The movement and operation of the working machine are controlled in accordance with the numerical data readout from the memory. It is apparent that such a numerical control system is very complicated in construction and expensive. Moreover the operation of the machine is exclusively controlled in accordance with the previously determined program and thus could not be changed upon the actual working and lacks flexibility. In other words the piercing points, start and end points of copying, etc. could not be simply changed in accordance with the shape and material of object, the shape of the pattern and arrangement of patterns. In practice, the numerical control system is quite inconvenient for effectuating particular operations.
Upon operating the known copying apparatus the operator has to control or command the operation of the working machine as well as the movement of the working machine into given positions. For instance, in the copy gas-cutting machine after the tracer has been moved into a piercing point the gas torch is rendered operative to produce a jet of cutting oxygen by operating a suitable member on a control panel. When the tracer has reached a copy end point the oxygen flow is stopped and the tracer is moved into a next piercing point. Then the cutting oxygen gas flow is again jetted from the gas torch. The above mentioned operation is rather cumbersome and results in a decrease in operation efficiency. In the numerical control system these operational functions of the working machine can be previously stored in a memory, and during the working the operational function of working machine can be controlled by reading out the command signals from the store. However as described above the numerical control system is very complicated and expensive and further the flexibility is lacking.